This invention relates generally to round electrical boxes and, more particularly, to an extender for such boxes that enables compliance with a certain provision of the National Electrical Code.
Article 370-20 of the National Electrical Code requires that in walls or ceilings of concrete, tile or other noncombustible material, electrical boxes shall be installed so that the front edge of the box will not set back of the finished surface more than 1/4" or 6.35 mm. It is also provided that in walls or ceilings constructed of wood or other combustible material, electrical boxes shall be flush with the finished surface or project therefrom. In many applications, it is not possible to meet these requirements of the National Electrical Code using conventional 4" round plastic nail-on electrical boxes, such as the Carlon B120A electrical box, for example. This is because the height of these boxes does not permit them to be mounted such that the front edge thereof is flush with the finished surface, as required by the National Electrical Code. Electrical inspectors are therefore presently unable to enforce compliance with the Article 370-20 of the National Electrical Code in applications in which use of these conventional round boxes do not permit compliance.
The present invention provides an extender for a conventional round electrical box which permits the user to incrementally extend the height of the box, as required in a particular application. The extender is adapted to fit inside the electrical box and to extend the height of the box, as determined by the thickness of a spacer placed between mounting ears of the extender and mounting columns of the box that are aligned when the extender is inserted into the box.